Add default alarm ringtone to sound settings.

Bug: 25957833
Change-Id: I68d6747894665c97853eabac7edb0f751d1fdcc1
diff --git a/res/xml/sound_settings.xml b/res/xml/sound_settings.xml
index 2cdebc4..dd03fb0 100644
--- a/res/xml/sound_settings.xml
+++ b/res/xml/sound_settings.xml
@@ -81,6 +81,14 @@
                 android:persistent="false"
                 android:ringtoneType="notification" />
 
+        <!-- Default alarm ringtone -->
+        <com.android.settings.DefaultRingtonePreference
+                android:key="alarm_ringtone"
+                android:title="@string/alarm_ringtone_title"
+                android:dialogTitle="@string/alarm_ringtone_title"
+                android:persistent="false"
+                android:ringtoneType="alarm" />
+
         <PreferenceScreen
                 android:key="cell_broadcast_settings"
                 android:title="@string/cell_broadcast_settings" >